Method of making range boilers



July 12, 1938. P. FOWLER METHOD OF MAKING RANGE BOILERS 2 Sheets-Sheet 1 Original Filed Dec. 27, 1935 4 TTDR/VE y" 2 Sheets-Sheet 2 MEN TU P L. FOWLER TURNE P. L. FOWLER July 12, 1938.

METHOD OF MAKING RANGE BOILERS Original Filed De c. 27, 1935 Patented July 12, 1938 UNITED STATES PATENT OFFICE 5 Claims. (Cl. 29-1574) This invention relates generally to range boilers, and particularly to a method of making same.

The main object of this invention is the con struction of a hot water boiler from inexpensive metal and to so treat the interior of the boiler that it will be fully protected against corrosion due either to the free oxygen in the water or to acid or alkaline properties of the water.

The second object is to so construct the boiler as to lend itself to the application of the prof tecting materials.

The third object is the development of a boiler which will have its entire inner surface covered with a sanitary, durable and rust-proof coating.

I accomplish these and other objects in the manner set forth in the following specification as illustrated in the accompanying drawings, in which:

Fig. 1 is a vertical section through a tank and a supporting stand showing the frit inserted into an inverted tank.

Fig. 2 is similar to Fig. l, but shows the tank opening closed with the tank right side up and having its upper end covered with a paste made of the frit.

Fig. 3 is a partial section through a tank in a horizontal position.

Fig. 4 is a section taken along the line fitl in Fig. 3.

Fig. 5 is a section taken along the line 55 p in Fig 3.

Fig. 6 is a fragmentary section on the lower end of a boiler showing the surplus frit being drained therefrom.

Fig. 7 is a view similar to Fig. 6 illustrating the improvement of -a special form of scraperfor removing the excess of frit from the bottom of the boiler.

Fig. 8 is a plan of the scraper shown in Fig. '7.

Fig. 9 is a sectional view through the boiler drying apparatus showing two boilers therein, one

of which is in partial section.

Fig. 10 is a vertical section through a finished boiler.

Similar numerals refer throughout the several views.

Referring in detail to the drawings, the boiler about to be described consists of a cylindrical shell ll having a convex top I2 and a convex bottom l3 which is disposed somewhat above the lower edge I4. The top I2 is provided with an butlet opening l5 and the bottom i3 is provided with an inlet opening Hi.

to similar parts causes for failure in enamel boilers.

The boiler thus far described is similar to those in common use except that the bottom is convex instead of concave for reasons which will become apparent later.

In the construction of a boiler care is taken to employ a metal, preferably steel, which by reason of its porous nature is especially adapted to form a bond with enamel, special pure steels being on the market for this purpose, and these are characterized by having extremely porous surfaces. It is also necessary that the boilers when formed be as smooth as possible on the interior and that no external corners be presented for enameling since it is difiicult to insure a proper covering thereof. The joints in these boilers are preferably of the butt type and special care is taken to remove all fins and irregularities from the interior of the boiler.

After the boiler is thus formed, it is subjected to approximately 250 pounds of water pressure for the purpose of testing the strength of the tank and removing the initial stresses prior to the application of the enamel. This is extremely important and eliminates one of the principal The boiler is then annealed, then pickled and then thoroughly neutralized and washed for the purpose of removing the scale from the interior of the boiler.

The boiler is now ready for the application of the frit. To accomplish this satisfactorily there is provided a pair of standards 23 on whose horizontal shaft 24 is mounted a tiltable frame 25 on one end of which is secured a bracket 26, which is normal to the frame 25 and carries an anti -friction bearing 2'? which is provided with an opening 28. At the opposite end of the frame 25 is mounted a slide 29 which has formed theregage a slidable rod 38 which is connected to a foot pedal 39. The rod 38 is urged upwardly by means of the spring 40.

The boiler H is placed upon the bearing Zl and the bearing 3| is brought downwardly upon the bottom l3 by means of the hand lever 34 where it is latched in position, as shown in Fig; 1. 4 A plug 4| is now inserted in the opening l5 and a funnel 42 is inserted downwardly through the bearing opening 32 and the opening I5.

There is now inserted into the shell l l a quantity of frit 43 in a soft paste form. This frit is of a special elastic kind which is useful principally as a priming coat and while its appearance is less sightly, it is especially adapted for this work on account of its non-chipping property. A plug 44' is now inserted into the opening I6 and the boiler l I is thereby completely closed.

It is desirable to provide rollers 45 on the frame 25 for the purpose of guiding the boiler ll into its correct position on the frame 25 and for supporting a portion of its weight when the boiler I I is in a horizontal position.

The boiler ll is now rotated to the position shown in Fig. 1 causing the frit 43 to thoroughly cover the lowermost end of the boiler l l, which in this case is in reality the top I2. The boiler II is then turned to a horizontal position by first releasing it by the operation of the foot pedal 39 which causes the latch Jill to withdraw from the segment 36, then to reenter the notch 31 when the boiler II has reached the horizontal position shown in Fig. 3. The boiler H is then rotated on a horizontal axis for the purpose of coating the cylindrical sides of the boiler ii.

The boiler I l is then moved to the vertical position shown in Fig. 2 by first manipulating the foot pedal 39 and again rotated by which time the entire interior of the tank is thoroughly coated with frit leaving a surplus within the tank. The plug 44 is now removed and the surplus frit ilt is drained into the vessel 48.

In order to prevent an excessive accumulation of frit on the bottom I3, I have provided a curved scraper 41 whose teeth 48 ride onthe bottom l3. The scraper 41 has its shank 49 curved downwardly and secured to the rim of a tubular nozzle 50. The manual rotation of the downwardly pro jecting nozzle 5|] causes the scraper 4! to rotate over the surface of the bottom I3 and remove any excess accumulation by way of the nozzle 50.

The boiler II is then placed upon a platform 5| provided with openings 52 over which the boilers are placed. The platform 5I forms the cover for an air box 53. The motor 54 drives a fan 55 which forces air through a radiator 56 causing warm air to flow from the air box 53 through the holes 52 and thence through the boilers.

It is desirable that the drying operation be gradual in order to prevent the surface of the coating from drying faster than the portion nearest the metal which would be apt to produce checks. -When the moisture is driven off, the boiler is placed in an oven and subjected to a suitable temperature in order to fuse the frit and form the desired coating over the interior of it.

It will be understood that prior to the baking steps all of the frlt is removed from the threads within the openings I5 and I6. This is ordinarily accomplished by running a tap through these openings.

The boiler is now inspected by illuminating the interior and observing the inner surface thereof It can be seen from the foregoing that a boiler so constructed and processed results in the formation of a boilc. which is not especially beautiaieaiea ful in the interior thereof, but is impervious to the action of water and not subject to chipping or checking under ordinary handling or abuse.

It must be understood that although large tanks, such as those used for transporting milk have been enameled on the interior thereof and that fittings of various kinds have been enameled inside, no one has successfully enameled range boilers due to three factors, which separately and in combination with each other render this prob-- lem a difficult one to solve. In. the first place, un' less the protecting enamel covers the entire surface, lt is almost as useless as if it covered none of it. To apply enamel to the interior of a small range boiler is a much different problem than to apply it to a large milk tank into which a man can enter for the purpose of smoothing the iu-- terior, applying the frit, and inspecting same after completion.

The second lactor is the difficulty experienced in preventing enamel from chipping and ore ting after it is once applied. This is accomplished by the removal of the initial stretching.

The third factor is the overcoming of the action of the frequent and sudden changes of ternperature in the boiler itself due to the rapid placement of the heated water and the subscquent refilling of cold water to which problem is added the injurious action of water hammers.

I have satisfactorily overcome these probl first, by constructing the boiler in a form which lends itself to the application of the frit,thro.gh the small end openings; secondly, by the removal of the initial stresses; thirdlyby insuring a uniform application of the frit and the removal ol any heavy surplus which may collect at the bottom during the draining period; and fourth, by the employment of the gradual drying of the frit it-- self. Another advantage inherent in my method resides in the fact that the frit may be applied in a condition which is most conducive to the formation of a coating of uniform thickness.

The various steps which have been outlined herein all contribute their portions to the solution of the difficulties above mentioned.

This application is a continuation in part of my application for a patent on a Hot water tank and method of producing same, filed October 24, 1934, Serial No. 749,756.

It must be understood that the purpose of stretching the material in the boiler after it is fabricated, but before it is enameled, is three-fold. First, it constitutes a test of the boiler under a pressure which is far greater than any which will be encountered under service conditions. Second, it serves to balance the stresses in the boiler walls by placing a permanent set in the structure thereof, and third, it expands the boiler walls to maximum dimensions at an excessive pressure which permanently sets the boiler in a form which is most nearly cylindrical along its length and curved to sustain a maximum load at its ends.

I claim:

1. A method of constructing range boilers consisting of forming a tank into a desired shape and then subjecting the tank to an excessive internal pressure in a manner to produce a permanent set therein after it is fabricated into tank form, and then enameling the interior of said tank.

2. A method of constructing range boilers con- 'sistingof progressively fabricating tanks into the .desired shape, then subjecting the tanks to an excessive internal pressure for the purpose of. producing a permanent set in the tank wall thereby causing the body of said tank to assume the form a true cylinder, and then enameling the interior the tank.

3. A method of constructing range boilers havcylindrical bodies and outwardly rounded ends consisting of fabricating the structure of the boiler to a .iorm which approximates the shape of a cylinder along its intermediate portion, then stretching the metal in said boiler by means of an excessive internal pressure to produce a permanent set therein and then enameling the interior surface of said tank.

4. A method of constructing range boilers having cylindrical bodies and rounded ends consisting of forming the boiler, then subjecting the boiler to internal pressure greatly in excess oil maximum working pressure for which the boiler is intended for the purpose of producing a permanent set therein, then applying a protective coat- Y ing of enamel to the interior of the boiler after it has been stretched.

5. A method of constructing range boilers consisting of progressively fabricating the boiler, then stretching the metal of said boiler to produce a permanent set therein and then enameling the interior of the stretched boiler.

PAUL L. WWLEE. 

